The generation of motion vector fields and disparity maps from motion video has long since attracted the attention of academics as well as the consumer electronics industry. The interest in motion vector generation received a substantial boost from the use of motion estimation and compensation techniques in video compression.
The pending introduction of 3D television and/or multi-view rendering equipment has similarly increased the interest in depth map and disparity map generation. Disparity maps and depth maps are commonly used in multi-view image generation from a single sequence of video images and enable the conversion of 2D video content into a format suitable for 3D television and/or multi-view rendering equipment.
Motion estimation can be used as a starting point for depth estimation. Estimation methods for motion vector fields often rely on the determination of similar image parts of consecutive images. As a single pixel value is insufficiently discernible to establish similarity, typically a group of pixels is used for establishing correspondence between image parts of consecutive images. As a result, the motion vector fields resulting from such estimation methods generally have a lower resolution than the original images. Some techniques for calculating motion vector fields calculate motion vectors for 8×8 pixel grids. As a result, when such a motion vector field is used for calculating a depth map the resolution will generally be too coarse for high quality rendering and will generally result in visible artifacts visible as halos at object edges.
Other techniques for depth map generation such as presented in WO2005/013623 “Multi-view Image Generation”, provide a full resolution depth map estimate at relatively low computational cost. First edges are established within an image and based thereon a depth map is generated by assigning respective depth map values to respective sides of the edge. Although the resolution of such depth maps is substantially higher than that of block based depth maps, the quality of the resulting depth maps can be further improved.